Punch holder with controllable lifting spring



May 24, 1955 P. H. TAY'LOR 2,708,970

Puncn HOLDER WITH CONTROLLABLE LIFTING SPRING Filed Jam 26, 1951 4 sheets-shet '2 77 770 I INVENTOR. Paul H. Taylor BY af rney.

May 24, 1955 P. H. TAYLOR 2,703,970v PUNCH HOLDER WITH CONTROLLABLE LIFTING SPRING Filed Jan. 26, 1953 4 Sheets-Sheet 3 Lw (Ll-Z0 770 1| INVENTOR. w Paul H. Taylor 4 BY Y 7 2,708,970 PUNCH HOLDER WITH CONTROLLABLE LIF TING SPRING Filed Jan. 26, 1953 P. H. TAYLOR May 24, 1955 4 Sheets-Sheet 4 72% uh {we kg/l ///.A[/A4/ Z T3. .m i. P w 7" 0 f E R W m jlriv m P fiaau P) 0 v A Z) A 5 m A w @4 w I A United States Patent PUNCH HOLDER WITH CONTROLLABLE LIFTING SPRING Paul H. Taylor, Grand Island, N. Y., assignor to Wales- Strippit Corporation, North Tonawanda, N. Y., a corporation of New York Application January 26, 1951, Serial No. 207,930

2 Claims. (Cl. 164-94) This invention relates to an improved portable punch and die holder of the type used in connection with presses and other machines for punching or perforating sheet metal, plates, bars, and various kinds of structural elements.

A machine provided with a holder for this purpose is disclosed in United States Letters Patent No. 2,364,011, granted to George F. Wales, November 28, 1944.

A holder of this sort, with its companion punch and die, can be readily inserted into and removed from the machine described in the above mentioned Wales patent. Also punches and dies of one size can be easily and quickly removed from the holder and replaced by punches and dies of other sizes.

Another type of punch and die holder is disclosed in United States Letters Patent No. 2,319,568 to George F. Wales, May 18, 1943, wherein a plurality of holders are detachably secured on the bed plate of a punch press, as by bolt connections, in dovetail or T-slots in the bed for simultaneously punching a number of holes in a workpiece or sheet of metal.

In punch and die holders such as are shown in the above mentioned Patents Nos. 2,319,568 and 2,364,011 and in United States Letters Patent No. 2,265,331 also granted to said George F. Wales, a stripper spring is engaged with the punch to disengage the punch from the punched work-piece, and a lifting spring of less capacity is also shown, which is employed to yieldingly lift and retain the punch and its guide sleeve, together with the stripper spring, in an elevated position to facilitate the insertion of work-pieces between the punch and die for punching.

Owing to variations in factors such as the weight of the parts, frictional resistance and breakage, such lifting springs at times fail to elevate the punch and associated parts to the proper retracted positions and to properly hold said punch and parts in such positions. Under such circumstances, the lower extremities of the punch and associated parts may be permitted to extend into the path of the work-piece which is to be introduced between the punch and the cooperating die. This is objectionable as the punch and associated parts may be injured by the work-piece as the latter is manipulated. Also the lifting springs may become unduly flexed or expanded with the result that a punch may be raised to a position where it may forcibly abut against the press ram when a holder is being inserted into position between the ram and bed plate, with resulting damage to the punch.

One object of the present invention is to provide a punch and die holder of the type generally described having a lifting means which will be operative to support the punch and associated parts in the desired relation with respect to the die and which may be adjusted, as required, to maintain, or vary such relation.

A related objectis to support a removable punch, punch guide and stripper spring assembly by the use of a lifting spring mounted on a holder but which does not constitute a part of the punch assembly.

2,708,970 Patented May 24, 1955 Another object of the invention is to provide a punch and die holder of the sort mentioned, with which the preload position of a punch therein may be easily and quickly adjusted and maintained so that the cutting end of the punch is held in correct relation to the punch guide when in a retracted position.

A further object is to provide a lifting device for such holders which is readily movable with the punch assembly during punching operations, also to provide such a device for punch and die holders which is readily adjustable to different holding positions to operatively engage the punch and the punch guide and stripper spring assemblies which vary in dimensions and which require engagement of the device therewith at relatively ditferent elevations; and also to provide a device of the kind mentioned which will automatically assume a safety position, accomplished by initial adjustment, to prevent the device from engaging the press ram during removing or change of one punch assembly for another.

Another object of the invention is to provide means whereby the lifting and control device may be automatically retained in position on the holder when a punch assembly is absent from the holder.

A further object is to provide a holder of this kind with punch assembly lifting means such that the lifting means will suiiice for all assemblies which may be used in the holder thus eliminating the individual lifting means now in use on each such assembly.

In punch presses and like machines it is usual to provide rear and side stops or guides, mounted on the bed plate and adjustable to guide one after another of a batch of work-pieces of like dimensions into correct position to enable a hole, or a group of holes, to be punched in the same positions in all pieces.

It sometimes occurs that a relatively large number of like work-pieces, having the same marginal shape and dimensions are thus punched, and also that a small number of other work-pieces, all requiring the same set of punched holes as those just mentioned, but which have a smaller area or are of less cross dimensions, are desired.

Obviously, the last mentioned small group of workpieces cannot be accurately positioned in the press for punching by the use of the stops or guides set for the first or larger batch of work-pieces.

The shut-down time of the press to enable the stops or guides to be adjusted for a small batch of pieces renders the cost of production of such pieces undesirably expensive.

A further and important object of this invention, therefore, is to provide a punch and die holder with a device with which work-pieces may be accurately positioned for punching without engagement with stops or guide members on the bed plate.

A related object is to provide a punch and die holder with means whereby a punch may be operatively positioned to engage a work-piece in the press so that one or more prick punch marks or indentations on the workpiece may be used to co-operate with a punch in locating the piece in position for punching without engaging the piece with stops or devices on the press bed.

Other novel features and advantages of the present invention will appear as the following description thereof proceeds.

In the drawings forming part of the specification of this invention:

Figure 1 is a side elevation, partly in longitudinal vertical section, of a punch and die holder in which this invention is incorporated.

Figure 2 is a fragmentary plan view of the punch and die holder, partly in section, taken approximately on the line 2-2 of Fig. 1.

Figure 3 is a fragmentary horizontal section taken on line 3-3 of Figure 1.

Figure 4 is a vertical, section, partly in side elevation, showing the parts of the holder of Figure l in a different position, theholder being'mounted' on a press bed.

Figure 5 is a fragmentary, vertical sectional view, illustrating the use of :the invention for positioning a workpiece in a press without the aid of stops on the press bed.

Figure6 is a diagrammatic plan view showing a press bed plate with several punch and die holders and workpositioning stops in relation to a work-piece.

Figure 7 is a diagramshowing in full lines, a Workpiece punched in accordance with the arrangement of Figure 6, and illustrating in broken lines, a work-piece of lesser dimensions on which a similar punching opera tion is required.

Figure 8 is a view of the smaller work-piece shown in Figure 7, having indicating and prick punch markings thereon whereby it can be accurately punched by means of this invention without the use of stops on the press bed.

Figure 9 is a plan view of an irregularly shaped workpiece having thereon a series of prick punch marks for locating a set of punch and die holders in position for punching the work-piece.

Figure 10 is a diagrammatic plan view of a punched work-piece or sheet, and a smaller unpunched work-piece operatively secured thereto, to disclose a further use of the invention.

Figure 11 is a vertical section, partly in side elevation of another form of punch and die holder embodying the invention.

Figure 12 is a plan view thereof, showing a portion of a press bed in which it is mounted.

A punch and die holder of the general form disclosed in the above mentioned Wales Patents No. 2,265,331 and No. 2.319568 is illustrated in Figures 1-6, while a punch and die holder of different form, as disclosed in said Wales Patent No. 2,364,011 is shown in Figures 11 and 12. Both forms of holders are provided with the improved and novel punch assembly lifting and controi means of this invention.

In the form of the invention disclosed in Figures l6 the novel punch and die holder is indicated generally by the reference character B. This holder comprises a body portion having upper and lower horizontal arms and 22 connected by an upright shank 24. to provide between the arms a work-receiving throat 26.

The free end of the upper arm 20 is bored vertically at 28 for the reception of a bushing 30 in which is removably mounted a punch assembly, generally indicated at A, and the punch P of which is axially aligned with a die D, removably supported in a bore 32 in the lower arm 22.

Holders of this sort may be used, in various kinds of machines, such as a single-hole punching press, or in a machine such as a press brake where several holders are mounted on the bed plate of the machine to simultaneously punch a number of holes, of the same or different sizes in variously arranged required positions in a workpiece.

For the purpose of disclosing the novel features of this invention, the bed or plate 36 of a suitable press is shown. having formed in its upper face 38, a plurality of equally spaced-parallel T-slots 40. I V

The holders B may be of different lengths to provide throats 26 to accommodate work of varying sizes and to enable the punches to reach the locations to be punched. Any suitable means may be used to secure the holders on the bed plate, some of which may have to be angularly disposed.

In the holder shown in Figures l6 the lower arm 22 of each holder B is provided witha longitudinal, vertical slot 42 through which extend clamping bolts or members 44. The upper ends of these members have heads and washers 43 engaging the top face of the arms 22 below the top of the elevated die receiving section 45 0f th arm 22. The lower ends of the bolts 44 have nuts 46 thereon which may abut the undercut faces of the T-slots 40 in the bed plate. When a holder is positioned where desired, the heads 43 are turned so that the nuts 46 on the lower ends of the members 44 are tightened against the shoulders of the T-slots 40.

A suitable ram or pressure applying member R, forming part of the press, and normally at rest above and spaced from the tops of the punches i, may reciprocate to a lower position to drive the punches down through a sheet of metal or a work-piece W, and into the dies D (see Fig. 4) and then return to its upper position, Fig. l.

The punch assembly A, comprises, in addition to a punch P, a punch guide sleeve 50 which surrounds the lower portion of the punch and slidably engages a bore in bushing 30. The upper end of the punch P is threaded for the reception of an adjusting nut 52 which may be manipulated to position the lower flat cutting end 54 of the punch in precise position slightly within the lower end of the sleeve 59, for example a distance of one thirty-second of an inch (see Fig. l). The nut 52 is then secured in set position by a lock nut 56 at the top of the punch (see Fig. 4).

Surrounding the punch and engaging between the nuts 52, 56, and the top of sleeve '50, is a nested pair of stripper springs 53.. When thus assembled, the parts are pre-loaded on the strippersprings, and the stroke of the ram R is such that the stripper springs 53 are compressed and the punch P will pass through a workpiece W and enter the die a distance of one thirty-second of an inch to clear the work and insure discharge of the punched out blank. After return of the ram R to its upper position, the stripper springs 53 will expand to their original position and cause the punch to clear the work.

The punch is retained in the sleeve 50 by two set screws 60 the inner one of which has a slip-fit engagement with a flat face 62 on the punch, as shown.

In the Wales Patent No. 2,364,011 the parts of the punch assembly are yieldingly retained in pre-load position by a lifting spring disposed between the head of the guide sleeve 50 and the top of the holder arm 20.

In the other Wales patents, Nos. 2,265,331 and 2,319,568, above mentioned, springs of leaf type are used for this purpose.

The present, improved, punch assembly lifting and control means has been provided to overcome certain limitations in the use of the lifting means shown in the three patents just discussed.

The means for controlling the operation and use of a punch assembly, such as the assembly A and other like structures and to enable additional uses or advantages to be gained by its employment, includes a movable lifting lever or finger 76, extending lengthwise along the upper arm 2% of the punch and die holder B with one of its ends pivoted on the arm 20 at. a point remote from the punch assembly A on a transverse horizontal pivot 72. The lifting finger may have spaced lugs 74, thereon straddling a pivot supporting lug 76 on the arm 20 (see Fig.2).

At its free end the finger 70 extends beneath and in engagement with the bottom of an enlargement or head on the punch guide sleeve 50 and may be recessed to fit loosely about the sleeve body, as shown.

Intermediate its ends finger 70 is apertured at 78 for the reception of a vertical adjusting rod or bolt 80. This rod 86 is threaded and passes, downwardly from the finger 70 through a threaded bore 82 in the upper arm 20. At its lower end the rod has secured thereon a pair of adjusting nuts forming a stop 83, which, when turned in an appropriate direction, may engage the bottom of a seat 86 in arm 20,- to limit upward movement of the rod 80.

Between the finger 70 and a seat 84 in arm 20, an extension spring 85, coiled about the rod 80 is arranged to thereby yieldingly hold the free end of finger 70 against the punch guide sleeve head, as described.

A knob or finger piece 83 is fixed to the upper end of rod 80 above and engageable with the top face of lever 70.

By turning this knob in one direction or the other, the adjusting rod 80 may be moved up and down in the threaded bore 82 to thereby enable the lifting lever 70 to be adjusted into position the bear against and hold the punch assembly A, including the punch P, stripper springs 58 and the guide sleeve 50 in required position by engagement of the lever with the head on that sleeve until the lower end of the punch assembly is in exactly the required position, as shown in Fig. l. The lever 70 will be held in such position by spring 85.

Preferably the adjusting rod 80 may be frictionally held against unintentional rotation by a fiber plug 919 in a transverse hole 92 in holder arm 20. The plug is pressed against the rod 80 by a screw 94 threaded in the hole 92 as shown in Fig. 3. Other means could be used for this purpose.

In the setting of the parts as described, with the nuts 83 hearing in seat 86, the lifting finger 70, when adjusted, enables the punch assembly A to be accurately positioned and yieldingly held in its desired pre-load condition in its holder B and relatively to die D. At the same time, the upper end of the punch assembly is prevented by the nuts 83 from being elevated to a position where it might engage the ram R during insertion of the holder into position.

In the type of holder described above, the punches and dies generally remain in position after once having been assembled in the holders, nevertheless, during the absence of a punch assembly from the holder, the finger or lever 70 can not swing about its pivot 72 into an unsafe or undesired position since its upward movement is restricted by the contact of stop nuts 83 against seat 86.

During the working stroke of the punch P by ram action for punching holes through work-pieces W, the

guide sleeve is lowered also, until its bottom end engages the work. At this time, the head of the sleeve also swings the lever 70 downwardly about its pivot 72 against the action of spring 85. After punching, the spring 85 will automatically return the punch assembly A through lever 70 to its upper position, ready for another punching operation, and also hold the parts in position, for a change in punches.

In order to illustrate the further uses and advantages of the punch assembly control device of this invention, an example is shown in Figures 6 to 8 wherein four of the holders B are secured in the T-slots of a bed plate 36 for punching four holes w, w1, W2, and W3 in the work-piece W, see Figures 6 and 7.

To enable these four holes to be punched in the same location on a considerable number of plates or workpieces W of the same size, guides or stops 100 of suitable construction may be provided, as is usual. The stops 100 shown are vertical studs, each carried in a member 102 having clamp devices 104 for securing the stops where desired by clamping engagement in the T- slots 40 of the bed plate. Thus two angularly related marginal edges x and x1, for example, of a piece W may abut the stops when thepiece W is pushed into the throats 24 of the holders B.

After each plate or piece W is thus positioned, operation of the press ram R will engage and simultaneously depress and force the punches P in the four holders through the piece.

It will be understood that the control devices described will all have been set in the manner explained, and will automatically lift the punch assemblies A of the several holders B to a retracted position. In this position clearance is provided between such assemblies and the respective dies D for insertion of another work-piece into position against the stops 100.

It sometimes happens that, while a relatively large number of like pieces, such as the piece W for example, may require the same set-up of punch holders for a series of like holes ww3, a relatively small number of plates W1 of lesser dimensions than the plates W may also require the same set of holes w-w3 to be punched therein, as indicated in Figs. 7 and 8.

Here the margins x2 and x3 of such plates W1 will not be correctly positioned relatively to the holders B of Fig. 6 without first repositioning the stops 100. Un-

der such conditions the shut-down time of the punch press to change the position of the stops, together with resulting labor cost may be considered to be undesirably expensive, adding to the total cost of each of those few pieces relatively to the cost in making each of the pieces W.

Hence further advantages to be had by the instrumentalities of the present invention are available to avoid the need of resetting the stops 100, or, in fact, the use of any stops.

In Fig. 7 a work-piece W, such as is present in Fig. 6 is shown after being punched and removed from the press, with the four resulting holes w-w3 indicated.

Upon the work-piece W, there is indicated in dot and dash lines, for comparison, one of the work-pieces W1 of Fig. 8.

To make a series of holes in a piece W1 to register with those in the piece W which is of greater area, the centers for at least two of the holes, such as the holes y and y2, are scribed on each plate W1 with the usual center marks. Then such center marks, chosen preferably at some distance apart, are indented by the use of a prick punch or similar tool to provide a conical recess, as indicated at 110, Fig. 8, and also in section in Fig. 5. These indentations are used as guides for positioning pieces W1 in correct relation to the punches, as set up in Fig. 6 without engagement with stops 100.

To do this two of the punches P of Fig. 6 corresponding to the locations of the guide indentations 110 on a piece W1 are removed from the punch assemblies and replaced by modified punches 111, such as that shown in Fig. 5. These punches are of the same diameter and cross section as those which were removed and have similar flat bottom faces 54.

Protruding from this bottom face 54 of punch 111 and disposed axially of the punch is a conical center point 112, substantially similar in shape to that of the point of the prick punch used to make the indentations 110 in the piece W1.

After the two punches 111, each with a center point 112 have been secured in their holders B in correct relation to other parts of the punch assemblies A, the rods 80 of the corresponding control devices on the holders are rotated by their handles 88 to force the levers or fingers 70 downward and against the action of their springs 85. The stops 83 will then recede from their seats 86. Each of the punch assemblies, due to its weight, will follow down, resting on the end of lever 70 until the center point 112 thereof engages the top face of a work-piece W1 which has been slid into approximate position for punching.

If the work-piece is now shifted about, the two center points 112 of the punches P will eventually drop into their desired guide apertures due to the weight of the assemblies and the lowering of lever 70. The operator can feel when this action takes place.

Piece W1 is now in position for punching, andwhen removed, other pieces of same size and thickness may be likewise correctly positioned by the foregoing procedure and punched by pushing them one after another into the press. The advancing edge of each piece, upon engaging the conical center points will cam the corree sponding punch assemblies upwards to allow passage of the piece beneath the two lowered punches.

The other punches P of the set-up in Fig. 6 are left unchanged and occupy positions as in Fig. l.

A further use of the invention is suggested in Fig. 9 wherein is shown an irregularly shaped plate or workpiece 120 having thereon scribed lines 122 for locating the centers of a series of holes which it is desired to punch in the work-piece.

By the use of a prick punch or the like tool, the centers for each of the desired holes may be provided with an indentation 124 similar to the indentations 119,

Figs. and 8.

Assuming that such a work-piece, or several of them, ar to be punched on a bed plate such as that at 38, Fig. 6, with a group of punch and die holders Ii, as there shown, the punches P in each holder would be p c ided with center punch protrusions 112 as in the arrangement described.

By this arrangement all the holders i3 can now be individually positioned for punching the pattern of holes on piece 120, by the use of punches P with center points 112 in all holders.

The center points 112 can be entered into the depressions 124 and the holders then clamped into position in the T-slots 40. It will, of course, be understood that in the foregoing proceeding the control or lifting lever 70 on each holder B will be adjusted and held down-- wardly, by the turning of rod 8i), so that the punch may be lowered to enable the center points to operate as described. This adjustment is to be seen in the holder shown in Fig. 11 where the parts are positioned to effect the foregoing result in that type of holder, as will be later set forth.

The advantages attained by the controlled lifting lever 5 Such indented piece or pieces 150a can be then oper- I atively positioned in relation to a group of punches, in holders such as B, Fig. 6, for punching holes similar to the holes 152, already punched in piece 150.

To effect this result, the punched workpiece 150 may be laid upside down and inscribed with long cross lines 162.

The position of these lines is determined by the required locations of the holes to be punched in piece In other words the centers of selected required holes from the edges 153 and 160, for example, of piece 1543a I '3 point 112 on a punch P may be entered in a conical prick being known and the distance between those holes and the corresponding edges 154 and 155 of plate 159 being greater, the lines 162 at those sides will represent the difference.

The plate or work-piece 156a is now correspondingly inverted and laid upon inverted piece 156 with the edges 158 and led registering with the scribed lines 162. The two pieces are now secured in this position by clamps 1'72.

The parts thus assembled are now turned right side up, as in Fig. 10. now inserted in this position into the press, and the edges 154 and 155 of piece 150 are engaged with the stops 1G8, punches P with center points 112 thereon, or perhaps only two of such punches may be struck to make two or more indentations 174 on piece 150a through holes 152 in piece 150a.

The pieces may now be removed from the press and separated.

Then by inserting the thus marked piece 15% with indentations 174 in the press, the center points on the If the clamped plates 15%, 150a are I punches which were used to mark that piece may be engaged into the punch marks 174, thus locating the piece in correct position to receive a punching operation without use of the stops 100.

In some instances, a punch having a chamfered cutting edge, as known in the art, could be employed in place of the punch having a center point, as described above.

In such procedure, the indentation of the work-piece 150a can be omitted, and that piece punched directly by such charnfered end punch, by placing the clamped together pieces 150, 150a into the press against stops 100, as described. Then the chamfercd end punches would pass through the holes 152 and then through unpunched plate 150a.

The holder B1 of Fig. 11, as stated, is of the type intended for use in a punch press or fabricator machine such as is disclosed in Wales Patent No. 2,364,011. In such machine only one holder is used, the latter being provided with a base 130 slidable into operative position in a groove or channel 132 in the press table 134, where it remains in use without need of bolts or other attachments.

A punch assembly supporting arm 136 similar to arm 20, Figs. 1 and 4, is spaced above and connected to base 130 by a shank 133. At its forward end this arm 136 is apertured to receive a punch assembly A, as before, including a punch guide sleeve 50, a punch P, and stripper springs 58 held against the head of sleeve by the nuts 52 and 56.

The base 139 is apertured for the reception of a die D1 the bottom face of which, when the holder is in place, rests on the bottom of the channel 132 to support the die in axial alinernent with the punch P. In this manner the die can be removed and replaced by another by drawing the holder out of the channel to a position in which the die clears its front edge. Then the die, upon being tapped lightly, will fall into the hand of the operator.

Similarly, the punch assembly can be lifted out of the arm 136, enabling the punches to be changed one for another in a few moments.

As seen in ll, the holder B1 is provided with one of the control levers 70, pivoted on arm 136 with its free end fashioned to engage and support the punch guide sleeve 50, as before.

Operation of the lever is by means of the adjusting rod 8% threadedly supported in the arm and having knob 88 for turning it for adjustment against the action of coil lifting spring 85.

The rod is provided with the stop nuts 83 (not shown), or their equivalent, for confining the lever within useful range, as in Figs. 1 and 4.

However, in the position shown, the lever 70 has been adjusted to lower the punch assembly A so that a center punch recess in a Work-piece to locate the piece in proper position to have a hole punched in a selected place.

This procedure may be repeated as often as necessary to operate upon one or several work-pieces.

' In the holder of the type shown in Fig. ll, the novel lever and spring punch lifting means is particularly desirable, since, with the frequent changes of punches and dies, only the one lever 70 is needed to control, by adjustment, when required, the lifting requirements of all punch assemblies used in the single holder employed in that type of machine.

It is believed evident from the foregoing that my irnproved and novel punch assembly lifting and control device enables better control of the punch assemblies of the type mentioned. Also more uniform support of such assemblies is provided.

Further, the device, when used to adjust punches having center points for engagement with work-pieces for locating such pieces in position for punching, also enables a number of like pieces to be easily and quickly positioned accurately in the press without use of stops.

The adjustment of the lifting lever for either type of use, also enables a punch press to be used to punch only one or a few pieces by means of the prick punch indentation and punch center point, at relatively low cost, so that pieces of diiferent dimensions may be provided with similar hole patterns.

The features of the invention are illustrated in connection with punch and die holders of the self-contained portable type. It is to be understood, however, that this is intended by way of example only and that the features of the invention may be employed to advantage in connection with various other types of apparatus and is not limited to portable apparatus.

I claim:

1. In a punching apparatus of the character described, a holder, a stripping sleeve reciprocable in said holder, a punch removably mounted in said sleeve and reciprocable axially therein, a die mounted in said holder in alignment with said punch, a spring interposed between said punch and said sleeve which is compressed during the working stroke of said punch and which expands upon completion of said working stroke to strip a workpiece from said punch, a rigid lever pivoted at one end on said holder and engaging at its other end with said sleeve, a spring disposed between the two ends of said lever and interposed between said lever and said holder to constantly urge said sleeve and said punch as an assembly to retracted position in spaced relation with rea holder, a stripping sleeve reciprocable in said holder, a punch removably mounted in said sleeve and reciprocable axially therein, a die mounted in said holder in alignment with said punch, a spring interposed between said punch and said sleeve which is compressed during the working stroke of said punch and which expands upon completion of said working stroke to strip a workpiece from said punch, a rigid lever pivoted at one end on said holder and engaging at its other end with said sleeve, a coil spring disposed between the two ends of said lever and interposed between said lever and said holder to constantly urge said sleeve and said punch as an assembly to retracted position in spaced relation with respect to said die, and a rod disposed coaxial with said coil spring and passing through said lever and the lastnamed spring and said holder, said rod being threaded at its inner end, a nut threaded on the inner end of said rod, said nut having frictional engagement with said holder to be held frictionally by said holder against rotation, said rod having an enlarged head at its outer end engaging said lever at the opposite side thereof from said coil spring to limit the retracting movement of said lever, said rod being rotatable by manual rotation of said head to adjust the position of said lever about its pivot and to adjust the limit of the retracting movement of said lever.

References Cited in the file of this patent UNITED STATES PATENTS 388,977 Hulme Sept. 4, 1888 494,311 Wills Mar. 28, 1893 770,239 Lovejoy Sept. 13, 1904 1,459,320 Corset June 19, 1923 1,533,236 Dawson Apr. 14, 1925 2,163,641 Wales June 27, 1939 2,412,066 Shear Dec. 3, 1946 2,421,500 Haff June 3, 1947 

